In an estimated 1-3% of the pediatric population, Obstructive Sleep Apnea (OSA) is likely responsible for many behavioral and neurocognitive dysfunctions. Recently the American Academy of Pediatrics highlighted the need to study the progression of pediatric OSA after surgical intervention. In previous studies, measures of neurocognitive function were based on behavioral tasks or questionnaires completed by the caregiver. A more objective and reliable measure of the efficacy of adenotonsillectomy (AT) for OSA is needed. I hypothesize that children diagnosed with OSA by overnight polysomnography (PSG) will exhibit differences in event-related potentials (ERPs) when presented with auditory and visual tasks that tap the cognitive functions of the brain's frontal lobes. High-density ERP techniques are safe and effective in children, and they provide insight into the electrical activity of the brain at the millisecond level. These time- locked waveforms can also be used to form spatial models which help localize electrical activity in the brain. ERP differences in childhood have been linked to behaviorally observed cognitive impairment and learning disorders. Differences, such as decreased peak amplitudes and increased latencies of specific waveforms discussed later in the proposal, might serve as markers for the cognitive deficits associated with sleep- disordered breathing. After AT, these measures should normalize. I propose to contribute to the current research by accomplishing three aims: (1) measuring cognitive and electrophysiological changes in children with OSA before and after surgery using ERPs;(2) examining the postoperative changes in clinical symptoms with behavioral tasks, standard neuropsychological assessments, and physiological measures, such as PSG;(3) obtaining the experience, instruction, and writing skills needed to become a functioning member of the scientific community. This proposal relates to the goals of NIH and NIMH in that it seeks to further understanding of the processes of neurobehavioral development with a focus on childhood (a period of rapid change during which the brain is particularly sensitive) and to employ several techniques to assess the severity of OSA and accompanying behavioral or psychological pathology. The proposed study will have a positive impact on public health by testing the extent to which sleep disorders like OSA affect the functioning of our children and assessing whether the commonly performed surgery actually resolves cognitive and behavioral problems. Increased awareness of the importance of sleep and treatment of sleep disorders in childhood is greatly needed. This study will further inform the scientific community and the public on the protection of sleep hygiene and the consequences and treatment of pediatric sleep disorders.